1. Field of the Invention
This invention relates to methods of and apparatus for forming peaks in a cover for a freight-carrying vehicle, and more particularly, to positioning a cover lifter at axial locations along the vehicle immediately following loading of the vehicle and observing the load to determine those locations at which one or more peaks need to be formed in the cover for transit, e.g., to tighten the cover and enable it to shed liquid during transit.
2. Discussion of Prior Vehicle Cover Supports
There are many types of open-top vehicles which are designed for carrying loads. For example, ocean-going barges, grain trucks and railroad gondola cars are all used to carry diverse loads. Some such loads are loose and form piles when dropped into the vehicle. Other loads include discrete rigid items (e.g., rolls of steel), which take up less than all of the space in the vehicle. In this case, each discrete rigid item of the load is in effect a pile in the vehicle. Piles of such loose material or such items may naturally form a peak (a load-peak) which extends above the horizontal plane defined by the top of the vehicle. In each case, as used to describe prior cover supports and the present invention, the word "load" includes such loose loads, such discrete items, and other things that form a pile upon being placed in a vehicle.
Reference is here made to load-carrying vehicles which are used when connected to other similar vehicles (such as gondola-type railroad cars), since problems encountered in the loading of one of such cars is compounded by the fact that a group of the cars is assembled into a unit, and not until after loading and covering all of the cars of the unit is the unit released from an industrial track, for example, onto the yard track or the main line. Therefore, delays in loading and covering any one car of the unit will delay the release of the entire unit, which delay can be costly to both the shipper and the railroad. Further, such gondola cars are typical of many vehicles which carry loads that form load-peaks.
As noted, a unit of cars must be quickly loaded and covered. With cost factors limiting the number of people in a typical yard crew to three people, under some current yard guidelines, it must not take more than fifteen minutes to cover each car. Further, care must be taken to avoid placing uncontrolled stress on covers which protect the loads. Such uncontrolled stress often exceeds the design strength of the cover, weakening it and reducing the protection of the load otherwise provided by the cover. When a cover is placed on such a loaded car, the load-peak is effective to form a corresponding load-peak in the cover. The load-peak does not usually extend along enough of the axial length of the car to prevent valleys from forming in the load, and thus in the cover. A valley is a place at which the load does not extend upwardly through the horizontal plane at the top of the car. Thus, the top surface of a load valley is below such plane. Depending on the load, there can be one or more valleys in the load anywhere along the length of the car.
A cover on the load-peak and the valley can be subject to such uncontrolled stress as the covered valley collects snow and water. Further, even when there is no snow or water in the valley, the cover tends to be loose over the valley, and on reaching speed during transit, the motion of the car through the air causes the cover to flap uncontrollably at the valley, causing a different type of uncontrolled stress on the cover. It may be understood then, that if the railroad yard crew simply loads the car, and then covers the load using a tightly fitting standard car cover or tarp, there will most likely be at least one peak and many valleys in the cover. During transit of the so-covered car then, there are many conditions which will subject the cover to uncontrolled stress. If the cover is not thereby ruined or severely damaged, the snow or water can significantly increase the weight of the effective load (intended load plus snow/water) carried by the car. Such high effective load, greatly in excess of the intended load, increases operating costs to an intolerable extent.
Others have recognized that such loads should not only be covered, but that the cover should be supported from underneath to supplement the natural load-peaks. One example of such supplemental support is the use of a factory-assembled cage having a standard length. The cage is designed to fit over a central axial portion of the railroad car. To accommodate cars of different lengths, end trusses and axial adjustment arrangements have been used at the ends of the cover and the cage. These form the cover into a double-ply joint at the end of the car, and fill in the gap between the end of the cage and the end of the car. In one approach to using such a cage, a cover is mounted over the cage after an axially extending ridge line is tied to ribs of the cage to space the ribs at a uniform distance apart. Significantly, that distance is set at the factory before it is known what type of car, and what type of load conditions, will be experienced by the railroad yard crew in the actual use of the cover and the cage. While benefits are said to result from this approach, a substantial disadvantage is the time required to mount the entire cage on the car even if the load has formed many of the above-noted load-peaks. In other words, by having to choose between using the entire cage which the factory specified and assembled or not using any cage at all, the railroad yard crew is not given an opportunity to select a particular type of cover support which is needed for the particular load which has been placed in the car. Thus, a given size crew must spend too much time erecting the cage or trying to add to the number of members in the crew. If the crew does not use the cage to support the cover, the crew risks having the uncontrolled stress ruin the cover. With crew sizes limited, and shippers requiring that loads such as rolled steel be covered at all times, in using the pre-set cages, the limited size crew has to work too fast, risking injury. Further, the unnecessary parts of the cage add to the extra weight carried by the car, and increase the cost of the supports needed to keep the cover peaked over the load valleys. All of these factors add to operating costs without generating revenue.
As a result, there is still a need to provide a way to support a vehicle car cover to form one or more yard-crew-defined-peaks therein at axial locations selected by the yard crew working at the switch yard or other loading site.
Users of other vehicles have been faced with the need to form a compartment above the bed of a pick-up truck. In this situation, a false floor has been provided by hinged rigid doors above the true floor or bed of the pick up truck. The hinged doors allow access to the storage space of the compartment below the false floor, while providing a strong floor for use under a tent or similar structure mounted over the truck bed. In one such system, the doors combine to cover the entire bed of the truck. Brackets mounted on the top of the opposite walls of the truck are adjusted axially along those opposite walls. Corresponding brackets on opposite sides of the walls form a bracket pair. At each axial end of the doors, a rod/turnbuckle assembly extends across the open bed and has ends connected to the pair of brackets to support a central hinge beam extending from the bulkhead to the tailgate along the longitudinal axis of the truck bed. The beam has a hinge connected to the doors to allow the doors to pivot to an open position and provide access to the storage space under the doors.
There are numerous examples of vehicle cover supports which use transversely extending upwardly pre-arched ribs mounted on opposite walls of the vehicle. In some cases, the ribs are allowed to move out of the way of loading operations. However, such ribs do not solve the time problem, and because in general all of the ribs stay on the vehicle all of the time, the weight problem is not solved either.